Merge pull request #11 from SuranjanDaw/master

Dijktras Shortest Path Algo Added

DijktraShortestPath/dijktras.c

@@ -0,0 +1,208 @@
+#include<stdio.h>
+#include<stdlib.h>
+#include<limits.h>
+
+typedef struct node node;
+
+typedef struct graph graph;
+
+struct node{
+  int name;//name of node
+  int dis;//its distance from origin
+  int size;//list size
+  int visit;//visited or not
+  int* list;//its adjacent list
+  int* wt;//weight of adjacent list
+};
+
+struct graph{
+  int V;
+  int E;
+  int* pre;
+  node** node_list;
+};
+
+node* createnode(int value, int* list,int* wt,int n)
+{
+  int i= 0;
+  //printf("%d\t", n);
+  //n = 3;
+  node* nptr = (node*)malloc(sizeof(node));
+  nptr->visit = 0;
+  nptr->dis = INT_MAX;
+  nptr->name = value;
+  nptr->size = n;
+  nptr->list = (int*)malloc(sizeof(int)*n);
+
+  for(i=0; i< n; i++)
+  {
+    nptr->list[i] = list[i];
+  }
+  nptr->wt = (int*)malloc(sizeof(int)*n);
+  for(i=0; i< n; i++)
+  {
+    nptr->wt[i] = wt[i];
+  }
+
+
+  return nptr;
+}
+
+graph* creategraph()
+{
+  int i = 0,j=0, e = 0, n=0, k = 0;
+  graph* g = (graph*)malloc(sizeof(graph));
+
+  printf("Enter the number of vertices and edges:");
+  scanf("%d", &n);
+  scanf("%d", &e);
+  g->V = n;
+  g->E = e;
+  g->pre =(int*)calloc(n,sizeof(int));
+
+  g->node_list = (node**)malloc(sizeof(node*)*n);
+
+  printf("Enter the details:\n" );
+  for(i=0; i< n; i++)
+  {
+    printf("For node %d:\n",i+1 );
+    printf("Enter the adjacency list size:\n" );
+    scanf("%d", &k);
+
+    int* li = (int*)malloc(k*sizeof(int));
+    int* w = (int*)malloc(k*sizeof(int));
+
+    printf("Enter the node numbers and weights\n");
+    for(j =0; j<k; j++)
+    {
+      scanf("%d",&li[j]);
+      scanf("%d",&w[j]);
+      li[j]--;//to  match the starting to zero
+    }
+    //printf("%d\t",k);
+    node* nptr = createnode(i,li,w,k);
+
+    g->node_list[i] = nptr;
+    k =0;
+    nptr = NULL;
+    li = NULL;
+    w = NULL;
+  }
+  return g;
+}
+
+int search(node** t,int n)
+{
+  int i =0; int flag = 0;
+  int size = n;
+  node* min = (node*)malloc(sizeof(node));
+  min->dis=INT_MAX;
+  /*for(i=0; i< size; i++)
+  {
+    min = t[i];
+    //printf("TestKey3\n" );
+    if(min->visit == 0)
+    {
+      //printf("TestKey2\n" );
+      break;
+    }
+  }*/
+  //printf("%d\n",min->name );
+  for(i = 0; i< size; i++)
+  {
+    //printf("TestKey\n" );
+    if(min->dis > t[i]->dis && !t[i]->visit)
+    {
+      //printf("TestKey1\n" );
+      min = t[i];
+      flag = 1;
+    }
+  }
+  if(!flag)
+    return -1;
+  return min->name;
+}
+
+void printPath(int* pre, int dest)
+{
+  if(pre[dest] == -1)
+    return;
+  printPath(pre, pre[dest]);
+  printf("%d-->", dest+1);
+}
+
+void dijktra(graph* g, int source, int destination)
+{
+  int key = source,i=0;
+  int n = g->V;
+  node* temp = g->node_list[key];
+  temp->dis = 0;
+  printf("%d\n",temp->name );
+  printf("%d\n",temp->dis );
+  while (n>0) {
+
+    temp = g->node_list[key];
+    printf("temp->name=%d\n",temp->name);
+    temp->visit = 1;
+    int num = temp->size;
+    for(i=0; i< num; i++)
+    {
+      //printf("temp->dis=%d\n",temp->dis);
+      int adj_lable = temp->list[i];
+      node* temp1 = g->node_list[adj_lable];//temp1 is the node on the adjacency list of temp
+      if(temp1->dis > temp->dis + temp->wt[i])
+      {
+        printf("temp->dis=%d\ttemp1->name=%d\ttemp->wt[i]=%d\n",temp->dis,temp1->name,temp->wt[i] );
+        temp1->dis = temp->dis + temp->wt[i];
+        g->pre[adj_lable] = temp->name;//
+        printf("temp1=%d\n",temp1->dis );
+        //temp->list[i]= temp->dis + temp->wt[i];
+      }
+    }
+    key = search(g->node_list,g->V);
+    if(key == -1)
+      break;
+    //printf("key=%d\n",key );
+    /*if(key == destination)
+      break;*/
+    n--;
+  }
+  g->pre[source]=-1;
+  printf("%d-->", source+1);
+  if(g->node_list[destination]->dis != INT_MAX)
+    printPath(g->pre,destination);
+  else
+    printf("No path\n" );
+  printf("\n" );
+}
+void print(graph* g)
+{
+  int i =0,j=0;
+  int n = g->V;
+  for(i =0; i<n; i++)
+  {
+    node* t = g->node_list[i];
+    int n1 = t->size;
+    //printf("%d\t", n1);
+    for(j =0;j<n1;j++)
+    {
+      printf("node_name=%d--",t->list[j]+1);
+      printf("wt=%d\t",t->wt[j] );
+    }
+    printf("u=%d\t",t->dis );
+    t = NULL;
+    n1 = 0;
+    printf("\n");
+  }
+}
+int main() {
+  int starting = 0;
+  int ending = 0;
+  graph* g = creategraph();
+  print(g);
+  printf("Enter the starting vertex and enfing vertex:" );
+  scanf("%d %d",&starting, &ending);
+  dijktra(g,starting-1,ending-1);//vertex numbers starts from 1
+  print(g);
+  return 0;
+}

DijktraShortestPath/input.txt

@@ -0,0 +1 @@
+6 8 2 6 4 2 1 2 3 7 6 2 1 4 3 1 5 2 1 3 1 1 5 1